package org.apache.maven.settings.building;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.List;

/**
 * Signals one ore more errors during settings building. The settings builder tries to collect as
 * many problems as possible before eventually failing to provide callers with rich error
 * information. Use {@link #getProblems()} to query the details of the failure.
 * 
 * @author Benjamin Bentmann
 */
public class SettingsBuildingException extends Exception {

  private final List<SettingsProblem> problems;

  /**
   * Creates a new exception with the specified problems.
   * 
   * @param problems The problems that causes this exception, may be {@code null}.
   */
  public SettingsBuildingException(List<SettingsProblem> problems) {
    super(toMessage(problems));

    this.problems = new ArrayList<SettingsProblem>();
    if (problems != null) {
      this.problems.addAll(problems);
    }
  }

  /**
   * Gets the problems that caused this exception.
   * 
   * @return The problems that caused this exception, never {@code null}.
   */
  public List<SettingsProblem> getProblems() {
    return problems;
  }

  private static String toMessage(List<SettingsProblem> problems) {
    StringWriter buffer = new StringWriter(1024);

    PrintWriter writer = new PrintWriter(buffer);

    writer.print(problems.size());
    writer.print((problems.size() == 1) ? " problem was " : " problems were ");
    writer.print("encountered while building the effective settings");
    writer.println();

    for (SettingsProblem problem : problems) {
      writer.print("[");
      writer.print(problem.getSeverity());
      writer.print("] ");
      writer.print(problem.getMessage());
      writer.print(" @ ");
      writer.println(problem.getLocation());
    }

    return buffer.toString();
  }

}
